1. Field of the Invention
This invention relates to centrifugal pumps and more particularly to such pumps effective for pumping slurry and which can chop stringy material, slice reasonably soft material such as vegetables and displace hard objects tending to obstruct flow into the pump intake opening of material to be pumped.
A difficult problem has been to pump slurries consistently and effectively. A slurry is a watery mixture or suspension of insoluble matter and may be of different consistency from a solid-material-to-water ratio of about 5 percent to about 25 percent. The term "slurry" is generic for different types of watery mixtures or suspensions of insoluble matter including mud which is a mixture of earth and water and pulp which is a mixture of animal or vegetable matter and water or other liquid. The pulp may be pulp of fruit such as apples, pears, peaches or plums for example, vegetables such as carrots or peas, other food products such as sugar cane, or wood such as used in the manufacture of paper. Pulp may also be a mixture of pulverized ore or white lead and water. All of these slurries are difficult to pump with pumps of conventional type. The pump of the present invention is capable of pumping such slurries satisfactorily.
2. Prior Art
The pump constitutes an improvement on the general type of pumps disclosed in U.S. Pat. No. 3,155,046, particularly as to effectiveness for pumping slurry. Also, the runners of pumps of the general type of U.S. Pat. No. 3,155,046 have included a shroud plate at the side of the runner opposite the intake wall of the pump casing, and such shroud plate has included a volute slinger serving to deter migration of the solid phase of a slurry into bearings of the runner shaft. In addition, rotary stirrers have been carried by the runner shaft at the side of the intake wall opposite the runner for the purpose of displacing articles which would not pass readily through an intake opening into the pump casing.